Method of reinforcing bridges and like structures



C. G. MORTENSON.

METHOD or REINFORCING 'smoees AND LIKE STRUCTURES.

APPLICATION FILED JUNE 25, l9l9.

Patented Feb. 24, 1920.

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oHAn Es nd-BENSON, or sAn FRANCISCO, CALIFORNIA.

'METI-IOD or nninroncme rmnsns AND LIKE s'rnuc'runns.

This invention relates to bridges and like structures, and particularly pertains to a method of reinforcing the same At the present time engineers are 'confronted with a problem in bridgeconstructien and repair which has proven quite diflicult. Due to the fact that traffic has increased over all highways and railways and that the tonnage of the traffic-is materially increasedfover the tonnage contemplated when bridges were built, and furthermore, to the weakened conditionof bridges which have arisen by the action of the elements and general deterioration, it has become necessary to replace many bridges or to provide some adequate means for reinforcing the brid e structures. As it is imperative that trafiicis not interrupted, it is more desirable to increase the capacity of bridges than it is to tear them away and build larger and stronger bridges sufficient to meet the traffic demands. And it is the principal object of the present invention to provide'means whereby the steel structures of both highway'and railway bridges may be adequately reinforced withoutinterrup tion of traflic and'by a method which will not only restore the bridge to its original strength, but provide any additional strength desired and further insure that he bridge, so reinforced, will be further protected against the action of the elements.

The present invention contemplates the use of stirrups or reinforcing caps which may be mounted upon the lower ends of bridge posts and which will receive additional cord and tension reinforcing members, cooperating with the original bridge structure, after which all of. the structural elements of the bridge are incased inconcrete to form a homogeneous, ferro conorete bridge structure of any pro-determined strength. I a i a The invention is illustrated by way of example in the accompanying drawings, in.

which Figure 1 1s a v1ew in side elevation showing a bridge partially relnforced by the 'Specificati ojrofLetters Patent. Patented Feb. 24, 1920. A Application filedflaune 25, 1919. Serial No. 306,596.

present method and as partially incased in concrete to form a ferro-concrete structure. Fig. 2 is aview in end elevation showing the portal of a partially completed bridge,

reinforced by the present method.

Fig. 3 is an enlarged fragmentaryview,

showing the manner of mounting the reinforcing members upon the bridge structure and partially disclosing the connections with the bridge abutment, one of the floor beams and one of the bridge posts, parts being broken away'for the sake of convenience; I

Fig. 4 is a view in transverse section through one of the chords fitted With corner angles.

In the drawings, a five-panel structural steel bridge is showmand it is the object of the present invention to provide means for reinforcing this bridge, and at the same time, increasing its strength. It will be understood that any type of bridge might be employed in carrying out the present method and in the present structure, a floor lOis provided and mounted upon transverse floor beams 11. The two center floor beams are supported by vertical posts 12,- while the outer beams are su ported by vertical rods 13. The ends 0 the floor are, of course, resting upon the abutments 14. Top chords 15 are provided and supported upon the upper ends ofthe post 12 and are further supported'at their opposite ends by end chords 16, theselatter chords rest,- ing upon the abutment. The structure is further tied together by a plurality of diagonal rods 17 connectingthe various chords 15 and 16 with the floor-beam structures and the posts 12. The bridge is tied to gether longitudinally by a plurality of chord rods 18, which are fastened to chord pins 19. These pins'are secured upon endplates forming a part of the fioor bean structures. a

When a bridge of the present type is to be reinforced, caps 20' are mounted over the lower ends of the posts 12 and alsoovei' the lower ends of the floor-beam structures intermediate the posts 12 and the abutments.

' These caps are clearly shown in Fig. 3 as having a bottom plate adapted to be fitted against the lower end of the post-structures and having side flanges which conform to the sides of the posts and floor-beam structures to prevent longitudinal movement. order to further stabilize the caps, plates 21 are secured to the bottom portions and extend upwardly between the panels of the structural members, this will act to hold the beam caps so that they cannot move and that any strain to which they are subjected will be directly transferred to the structures;

upon which they are mounted. The hangers which are disposed beneath the vertical posts 12 are supported by means of secondary diagonal 22, these members extend upwardly through the caps '20 and outwardly through the channel members of'the-posts I to besecured through the chord members 15 and 16. A block 23 is mounted beneath the caps and is formed with diagonal faces to receive the .nuts of the diagonal rods 22 and to permit these nuts, as indicated at 24,

l to be tightened. The chords are "provided with filler blocks25, which stand at an angle to the surface of thechords and act as bearing surfaces for nuts 26 upon the upper ends of the diagonal rods. The caps carry said tension rods 27, which extends through the posts and the caps and are threaded attheir opposite ends to'ireceive turn-buckles 28. Lock nuts '29 are provided to be mounted upon the caps and to hold the tension rods in position. The turnbuckles are designed to receive the ends of secondary cords 30, whichextend parallel to the original chord-bars 18. The tension rods 27 which extend through the structures of the end chords near the abutment are continued u wardly and pass through the foot of thechords 16, where they are secured by means of nuts 31,1which rest against filla blocks '25 as previously described. Further reinforcement of the structure is provided by transversely extending tie rods 32, which are connected with floor beams .and stand parallel there along, as shown in Fig. 2. By

the use of the tie-rods 32, it will be seen that thefloor will be more properly supported andrcan be reinforc'ed to carry any load desired.

l/Vith the structure comprising the original bridge and the elements previously described as being added, the final steps in the process may be made. At this time the frame-work may be inclosed in forms and completely embedded within concrete. as indicated in Figs. land 2. This will provide adefinite mechanical structure calculated to carry certain strains and stresses, which structure nowforms a part of a ferro-co'ucrete bridge of any predetermined capacity and having its vital elements protected by the surrounding concrete. 1

It will thus be seen that by employingthe present method a bridge may be reinforced and preserved without molesting any of the structural elements thereof, and by the addition of elements having pre-determined =ent is witnesses.

factors of. strength, the method resulting in providing a bridge of superior construction over the ori'ginal condition and design to accommodateanyload without having required an interruption of trailic or the prohibltiveexpense of tearing down the bridge and building a new one. 1

Reference. being had'to Fig. Al, it will be seen that the top and end chords are reinforced by corner plates formed "of angle iron. This construction will preventbreakage of the corners of the finished work.

, While I have shown the preferred method of carrying out the present invention, it will'be understood that various changes in the steps of the method might be made by those skilled in: the art,', without departing from the spirit-of theinventi'on, as claimed. Having thus described my invention, what I claim and desire to secure by Letters 'Pat- 1-.- A method of reinforcing and protect.- ing completed and u'sedbridges which consists in adding parallel diagonal and chord rods to the frame-work thereof, and thereafter embedding the beams and posts ofthe bridge in concrete to form a. ferro-concrete frame. r

'2. A. methodof reinforcing."completed 'bridgestructure-fat the ends. of the floor beams then a djustably connecting chord rods to said caps, then passing diagonal rods reconthrough'the caps and extending them up? wardly throu h the main bridge frame and thereafter emibedding the truss floor beams, the posts of the bridge frame and the main beams in concrete. v

4. A method for reinforcin-g'and protecting completed and 1.used steel bridgesand like structure's, consisting in connecting the chord members with means to increasetheir tensile resistance, :and embedding. said mem' hers, and the compression members, in 7 body of concrete. r

In testimony whereof I have'hereunto set my-hand in the presence of two subscribing CHARLES G. MORTENSON. WitnesseSr] HEALEY,

M. E. EWING. 

